1. Field of the Invention
The present invention relates to a transmission apparatus that holds a lock core of a lock, and more particularly to a transmission apparatus that aids precise installation of a lock core in an supplemental lock.
2. Description of Related Art
Generally, normal house and room doors need more than one lock to provide high security. Door locks are available in a variety types and structures for different applications. Trumpet locks, lever locks, doorknob locks and supplemental locks are commonly used to lock doors.
Trumpet locks, lever locks and doorknob locks are the primary locks used to lock doors. Supplemental locks provide security for doors in addition to the primary locks where the primary locks are part respectively of the doors or the doorknobs.
With reference to FIGS. 10 and 11, a conventional apparatus to hold a lock core (not shown) of a supplemental lock comprises a housing (50), an outer disk (52), a latch bolt coupler (53) and an inner disk (54).
The housing (50) has a front (not numbered), a rear (not numbered), a lock core chamber (51), a front opening (511) and a rear opening (512). The lock core chamber (51) holds a lock core (nor shown). The front opening (511) is defined in the front and communicates with the lock core chamber (51) and through which a lock core is mounted in the lock core chamber (51). The rear opening (512) is defined in the rear and communicates with the lock core chamber (51).
The inner disk (54) is rotatably mounted in the lock core chamber (51), is rotated by the lock core and comprises a rotatable base (541) and two lock coupling arms (542). The base (541) has a central though hole (543). The central through hole (543) is defined completely though the base (541) and has a keyway (544). The lock coupling arms (542) protrude longitudinally from the base (541) toward the front opening (511), are parallel to each other, connect to the lock core and are rotated by the lock core.
The outer disk (52) is rotatably mounted on the rear of the housing (50), covers the rear opening (512) and has a disk (520) and a protrusion (521). The disk (520) covers the rear opening (512) and has a rectangular through hole (522). The protrusion (521) extends from the disk (520) and is rotatably held in the rear opening (512). The rectangular through hole (522) is defined completely through the disk (520) and is aligned with the central through hole (543) in the base (541).
The latch bolt coupler (53) comprises a rectangular driving rod (531), an enlarged head (532) and a key (533). The rectangular driving rod (531) has an inside end (534) and an outside end (535). The enlarged head (532) and the key (533) are formed at the inside end (534), and the key (533) is aligned with and engages the keyway (544) in the base (541). The outside end (535) extends into the central through hole (543) in the base (541) and the rectangular through hole (522) in the disk (520) and extends out of the rectangular through hole (522) to connect to a latch bolt (not shown) to drive the latch bolt. The enlarged head (532) abuts the base (541) of the inner disk (54). The inner disk (54) will rotate the latch bolt coupler (53) that drives the latch bolt when the lock core rotates the inner disk (54).
However, assembling the conventional transmission apparatus that holds the lock core is inconvenient. First, the outer disk (52) must be mounted on the rear of the housing (50) with the protrusion (521) rotatably held in the rear opening (512). Then the inner disk (54) and the latch bolt coupler (53) can be mounted in the lock core chamber (51), and the outside end (535) of the driving rod (531) extends into the central through hole (543) in the base (541) and the rectangular through hole (522) in the disk (520) and extends out of the rectangular through hole (522) to connect to the latch bolt. Then the lock core is mounted in the lock core chamber (51) and connected to the lock coupling arms (542) to drive the latch bolt coupler (53) through the inner disk (54).
Since the outer disk (52), the latch bolt coupler (53) and the inner disk (54) are individually attached to the housing (50), the three elements do not mutually hold each other in position during the assembly of the apparatus. The outer disk (52), the latch bolt coupler (53) and the inner disk (54) cannot be efficiently held in position in the housing (50) before the lock core is mounted in the lock core chamber (51). This adversely influences the assembly and quality of the supplemental lock.
To overcome the shortcomings, the present invention provides an improved transmission apparatus that holds a lock core of a supplemental lock to mitigate or obviate the aforementioned problems.